Ever wondered why a guy didn't call you back? Rachel Greenwald has the answer. She spent ten years interviewing over 1,000 guys, and she lays it all out in her new book, Why He Didn't Call You Back: 1,000 Guys Reveal What They REALLY Thought About You After Your Date.

According to Greenwald, "there are more failed first dates today than ever before." With the popularity of online dating, singles have come to expect perfection. Because why wouldn't you, when you can land a new date with a few clicks of a mouse?

But when it comes to marriage-minded men, Greenwald's research reveals that there are clear, consistent reasons men don't call women back. It all comes down to stereotypes.

"You can't make a meaningful decision about whether that person is right for you from a first or second date," says Greenwald. But in order to decide if someone has long-term potential, guys (and gals) use small cues to make big assumptions about their date's personality, lifestyle and character. "People are making decisions about whether a relationship could ultimately work based on very superficial data points."

Greenwald's book encourages women to be aware of the image they're projecting, and to make small adjustments to their behavior so that they can land a second or third date. "I don’t want to change you," says Greenwald. "I want to change the way you come across on the first date."

Greenwald has an MBA from Harvard business school, and published her first book, Find a Husband After 35: (Using What I Learned at Harvard Business School), in 2003. She leads a successful matchmaking business, and used her own tactics to find her own husband, so she knows whereof she speaks.

YourTango spoke to Greenwald about why you should never Facebook friend a guy before going out with him, who should pay for dinner and the number one reason men don't call you back.

YourTango: What is a successful first date?

Rachel Greenwald: To me a successful first or second date is simply an invitation to go out again. You can't really get to know who the person is deep down until you spend more time with them, so the lack of a follow-up date invitation means that someone has quickly stereotyped you.

What's the most common reason guys don't call back?

The number one reason why men didn't call a woman back is what I call The Boss Lady. This is a stereotype of a women who is very accomplished and successful and frankly fabulous in so many ways, but the man walks away from the date thinking that he's more interested in hiring her than dating her. He thinks she's argumentative, competitive, not feminine, controlling and not nurturing.

This is NOT a reflection of whether he could be happy with a Boss Lady. He probably would be, because the traits that initially come across as bossy may later be deemed forthright or confident.

So, what do you do if you're a Boss Lady?

If a women identifies herself as a Boss Lady I don't suggest that she change her personality; I suggest that she show the softer side of herself first, before the stronger side emerges. A lot of that has to do with just changing how she speaks.

There's an example of a date in the book about a couple that goes to a dinner party and the man watches his date argue with another guest about global warming. She very aggressive and she's trying to win every point, and he thinks that she's very argumentative and competitive.

The right way to change your delivery would be to make a softer. You could say, "It's great to see this issue get so much attention. I guess we'll see who's right in the long run." The delivery of these statements is a very superficial thing. You're actually saying the same thing, but you're delivering it in a more gracious and open minded way.